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Must-know facts
20 facts
- 1Microbes survive in geysers at up to 100°C, under thick snow, deep in soil and in acidic places; prions are protein infectious agents.
- 2Curd: Lactobacillus (LAB); acids coagulate milk proteins; vitamin B12 rises.
- 3Idli and dosa dough: fermented by bacteria, puffed by CO₂. Bread: baker's yeast, Saccharomyces cerevisiae.
- 4Toddy: fermented palm sap.
- 5Swiss cheese holes: CO₂ from Propionibacterium sharmanii. Roquefort cheese: ripened by a fungus.
- 6Wine and beer: no distillation. Whisky, brandy, rum: distilled.
- 7Penicillin from Penicillium notatum; Fleming noticed it on a Staphylococci plate; Chain and Florey proved its worth; Nobel Prize 1945.
- 8Citric acid: Aspergillus niger. Acetic acid: Acetobacter aceti. Butyric acid: Clostridium butylicum. Lactic acid: Lactobacillus.
- 9Lipases in detergents; pectinases and proteases clarify fruit juice.
- 10Streptokinase (Streptococcus) is a clot buster for heart-attack patients.
- 11Cyclosporin A: Trichoderma polysporum, immunosuppressant. Statins: Monascus purpureus, lower cholesterol by competitive inhibition.
- 12Primary treatment: physical, filtration and sedimentation; gives primary sludge and effluent.
- 13Secondary treatment: aeration tanks, flocs of bacteria and fungal filaments, BOD falls; activated sludge settles, part returned as inoculum.
- 14BOD: oxygen used if bacteria oxidised all organic matter in one litre of water; higher BOD means more polluting.
- 15Anaerobic sludge digesters give biogas: methane, H₂S, CO₂.
- 16Methanogens (Methanobacterium) live in sludge and the cattle rumen; biogas plant tank 10-15 feet deep; IARI and KVIC.
- 17Ladybird eats aphids; dragonfly eats mosquitoes; Bt kills butterfly caterpillars; Trichoderma controls plant pathogens.
- 18Baculoviruses (Nucleopolyhedrovirus) are species-specific, narrow-spectrum insecticides suited to IPM.
- 19Rhizobium: symbiotic in legume nodules. Azospirillum, Azotobacter: free-living nitrogen fixers.
- 20Glomus forms mycorrhiza and supplies phosphorus. Anabaena, Nostoc, Oscillatoria fix nitrogen in paddy fields.
Common traps
Where marks are lost
Calling beer or wine a distilled drink.
Wine and beer are made without distillation; whisky, brandy and rum are the distilled ones.
Crediting Swiss cheese holes to a fungus.
The holes come from CO₂ made by the bacterium Propionibacterium sharmanii; it is Roquefort that is ripened by a fungus.
Swapping the acid producers.
Aspergillus niger (fungus) gives citric acid; Acetobacter aceti gives acetic acid; Clostridium butylicum gives butyric acid; Lactobacillus gives lactic acid.
Mixing up the two Trichoderma entries.
Trichoderma polysporum makes cyclosporin A; Trichoderma species in the root ecosystem act as biocontrol agents against plant pathogens.
Saying statins come from a bacterium.
Statins come from the yeast Monascus purpureus.
Thinking a high BOD means clean water.
BOD tracks organic matter; the higher the BOD, the more polluted the water.
Placing the anaerobic stage in the aeration tank.
Aeration tanks grow aerobic flocs; the anaerobic bacteria work later, in the sludge digesters, where biogas is made.
Calling primary treatment biological.
Primary treatment is physical (filtration, sedimentation); secondary treatment is the biological stage.
Listing Rhizobium as a free-living nitrogen fixer.
Rhizobium is symbiotic in legume root nodules; Azospirillum and Azotobacter are the free-living ones.
Key terms
19 terms
- Lactic acid bacteria (LAB)
- Bacteria such as Lactobacillus that turn milk into curd by making acids.
- Inoculum (starter)
- A small amount of a culture added to start fermentation, like curd added to milk.
- Fermentor
- A very large vessel for growing microbes on an industrial scale.
- Distillation
- The step that separates whisky, brandy and rum from undistilled wine and beer.
- Antibiotic
- A chemical made by a microbe that kills or slows the growth of other, disease-causing microbes.
- Streptokinase
- A clot-dissolving enzyme from Streptococcus, used for heart-attack patients.
- Cyclosporin A
- An immunosuppressant for transplant patients, made by Trichoderma polysporum.
- Statins
- Cholesterol-lowering agents from the yeast Monascus purpureus.
- Sewage
- Municipal waste water, rich in organic matter and microbes.
- Primary sludge
- The solids that settle out during primary treatment.
- Flocs
- Mesh-like masses of bacteria and fungal filaments that grow in aeration tanks.
- BOD
- Biochemical oxygen demand: the oxygen bacteria would use to oxidise all the organic matter in one litre of water.
- Activated sludge
- The settled flocs after aeration; part returns to the aeration tank as inoculum.
- Methanogens
- Anaerobic bacteria such as Methanobacterium that make methane from cellulosic material.
- Biocontrol
- Controlling plant pests and diseases by biological methods instead of chemicals.
- Bt
- Bacillus thuringiensis, a bacterium whose toxin kills caterpillars.
- Baculoviruses
- Insect-attacking viruses, mainly Nucleopolyhedrovirus, used as narrow-spectrum insecticides.
- Biofertiliser
- An organism that enriches the nutrient quality of soil.
- Mycorrhiza
- A symbiotic association of a fungus, such as Glomus, with plant roots.